Quick answer
Do not assume LPG and methane detectors belong at the same height. Methane is less dense than air, while vaporised LPG is heavier, so their likely movement differs. Density is only one input: the release source and ventilation also matter. The responsible designer should determine each position using the actual application and applicable detector documentation, not a universal height rule.
Density explains a difference, not a finished design
The HSE fixed-detector guidance, paragraph 57, contrasts methane's upward tendency with vaporised LPG's tendency to remain lower. It also relates gas movement to ventilation. This supports evaluating the two applications separately, not assigning a universal distance from the floor or ceiling.
A height recommendation without a gas identity, reference point and application is incomplete. Ask whether the proposed dimension refers to the sensing inlet, the enclosure or another defined feature. The installation drawing should remove that ambiguity before a contractor marks mounting holes.
Compare the assumptions behind each proposed point
Use this review table when two drawings show different heights, or when a supplier proposes the same arrangement for both gases. It asks for the reasoning; it is not a placement specification.
| Review question | LPG application | Methane application |
|---|---|---|
| What is being monitored? | Identify the supplied LPG and process | Confirm methane or actual gas mixture |
| Which release is being considered? | Reference the source register | Reference the source register |
| What supports the position? | Request the designer's stated basis | Request the designer's stated basis |
| Which drawing governs? | Record elevation and point reference | Record elevation and point reference |
Do not transfer a position during a fuel change
If a Malaysian kitchen or factory changes its fuel supply, flag the existing detector layout for review rather than assuming that replacing the sensor preserves the approved design. Send the old and proposed gas descriptions, equipment changes and current drawings together. Ask the project team to state which earlier assumptions remain valid.
Keep equipment selection and positioning as separate approvals. A supplier's confirmation of the intended sensing configuration does not itself approve the mounting point. Likewise, a designer's location approval does not establish that an unspecified detector variant is suitable for the new duty.
Ask for a usable installation decision
Request the final position on an elevation drawing, not just a verbal instruction to mount the detector 'high' or 'low'. The record should identify the detector tag, the physical reference used for the dimension, the applicable manual and the person responsible for design approval. Keep any unresolved information visible.
Where the proposed point conflicts with access, equipment or another contractor's work, send the conflict back for review. Moving the detector to the nearest convenient surface should not become an undocumented site variation. Record the revised decision in the same drawing set used for handover.
Keep the conclusion specific to the project
There is no single installation height supplied by this comparison. The useful conclusion is whether each proposed position has a documented basis for its gas and site, and whether that basis survives the actual installation conditions. An online explanation cannot confirm the adequacy of either location.
The existing UTAI LPG installation-height guide gives LPG project context. Use the UTAI installation guide for wider coordination. Neither link authorizes applying an LPG arrangement unchanged to methane.